GB1300660A - Improvements in motor driven impeller pumps - Google Patents

Abstract

1300660 Centrifugal pumps NIKKISO CO Ltd 14 Dec 1970 [6 Aug 1970] 59337/70 Heading F1C A motor-driven pump comprises an impeller mounted on a shaft 14 having a pair of main thrust bearings 22, 24 and co-operating thurst plates 18, 20, and also incorporates hydraulic thrust balancing means defining with the impeller at least one fixed orifice 34, variable orifice 36 and pressure chamber 40. Moreover, one of the side walls defining the variable orifice is constituted by a releasably-mounted auxiliary thrust bearing 38. The bearings are of a material which wears smoothly, e.g. graphite, plastics, ceramic or copper alloy, so that if the variable orifice gap becomes excessive, then the consequent wear at bearing 22 will have a corrective effect. Conversely, if the gap becomes closed then corrective wear occurs at bearings 24, 38. In other embodiments, the auxiliary thrust bearing is attached by a metal clamping ring, functions additionally as a journal bearing for the shaft, is carried by the impeller, is fixed to the wall of the pump housing adjacent the suction inlet, or co-operates with a special thrust ring provided on the impeller. Hydraulic thrust balancing means with respective auxiliary thrust bearings may be arranged at both sides of the impeller. Thrust plates 18, 20 may be subjected, during manufacture, to surface treatment such as metal plating or grinding to facilitate the smooth wear. All bearings are replaceable.